20 September 2012

Update 20 September:
EXTENT: Satellite data shows Arctic melt sea-ice extent probably reached the minimum for the year at around 3.4 million square kilometres on Monday 17 September, 18 per cent less than the previous record in 2007 of 4.2 m.sq.kms. The JAXA daily raw data is here and the NSIDC date is here. This extent is now well less than half of the average extent of the 1980s.

VOLUME: The sea-ice volume is now down to just one-fifth of what it was in 1979. Latest PIOMAS volume from September 3, 2012 is 3407 cubic kilometers of
ice remaining in the Arctic. Contrasted with the 16,855 of 1979, that is
just about 20 per cent. Extent has dropped further since 3 September, so minimum volume this melt season will be about 5–10 per cent less than the early-September figure.

ICE-FREE ARCTIC: Debate rages within the scientific community. Previously we covered Big call: Cambridge prof. predicts Arctic summer sea ice “all gone by 2015”. On Monday the Guardian reported "Arctic expert predicts final collapse of sea ice within four years", in which Prof. Peter Wadhams of Cambridge said: "I have been predicting [the collapse of sea ice in summer months]
for many years. The main cause is simply global warming: as the climate
has warmed there has been less ice growth during the winter and more ice
melt during the summer… in the end the summer melt
overtook the winter growth such that the entire ice sheet melts or
breaks up during the summer months. This collapse, I predicted
would occur in 2015-16 at which time the summer Arctic (August to
September) would become ice-free. The final collapse towards that state
is now happening and will probably be complete by those dates. As the sea ice retreats in summer the ocean
warms up (to 7C in 2011) and this warms the seabed too. The continental
shelves of the Arctic are composed of offshore permafrost, frozen
sediment left over from the last ice age. As the water warms the
permafrost melts and releases huge quantities of trapped methane, a very
powerful greenhouse gas so this will give a big boost to global
warming." Unforntunately, the eviednce is on his side.

The Arctic sea-ice big melt of 2012 “has taken us by surprise and we must adjust our understanding of the system and we must adjust our science and we must adjust our feelings for the nature around us”, according to Kim Holmen, Norwegian Polar Institute (NPI) international director.
From Svalbard (halfway between mainland Norway and Greenland), the BBC’s David Shukman reported on 7 September that Holmen had described the current melt rate “a greater change than we could even imagine 20 years ago, even 10 years ago”.
As detailed last week, the thin crust of sea-ice which floats on the north polar sea is now only half of the average minimum summer extent of the 1980, and just one-quarter of the volume twenty years ago.

Introductory note: It is now very likely that the Arctic will be sea-ice-free within a decade, with enormous consequences. Not only has the 2007 record minimum low been smashed, but the new record low 2012 sea-ice extent (3.4 million square kilometres) is less than half the figure three decades ago. And the volume of ice is now down to just one-fifth of the figure three decades ago. In 1979 the summer volume was 16,855 cubic kilometres, on 3 September this year it was just 3,407 cubic kilometres. 80 per cent of the ice has already been lost.
The IPCC 2007 got the Arctic sea-ice wrong in projecting an Arctic still containing summer sea-ice by 2100. Now, Arctic specialists relying on new, regional climate models such as Prof. Peter Wadhams of Cambridge are making the big call of a summer ice-free Arctic as early as 2015. By contrast, those relying for Arctic forecasts on global general circulation models (GCMs) used for the 2007 IPCC report are sticking to a 2030-2040 projection, but lament that “We just don’t know exactly why this (sea-ice loss) is moving so fast”. The predictions of those who rely too much on the GCM models seem strangely removed from the reality on the ground and even a common sense view of the evidence, as this analysis from Arctic News shows. Underestimating the speed and likely future rate of change in the climate system has deadly consequences. – David

10 September 2012

Something
extraordinary is happening when graphs of melting Arctic sea-ice have
their vertical axis redrawn because the data are falling off the chart.
But that’s what has occurred in the last 10 days, since the extent of floating Arctic sea-ice broke the satellite-era minimum record on 24 August. On that date it was 4.2 million square kilometres, according to data from the Japan Aerospace Exploration Agency.
Since then, an additional half a million square kilometres of
sea-ice has melted. The extent on 4 September was just half of the
average minimum extent of the 1980s. At the current rate of loss, with
one to three weeks left in the northern melt season, the minimum may
well shrink below 3.5 million square kilometres. This is an astounding
story.

09 September 2012

Arctic sea ice extent over the past 1,450 years reconstructed from
proxy data by Kinnard et al., with a 40-year low pass filter applied.
Note that the modern observational data in this figure extend through
2008, and thus it is a close approximation of current conditions, even
though the extent is not as low as current annual data due to the
40-year smoothing. Courtesy Skeptical Science

PICKS OF THE WEEK

Life Is Sacredhttp://www.truthdig.com/report/item/life_is_sacred_20120903/Chris Hedges, TruthDig, 3 September 2012Corporations care nothing for democracy, the rule of law, human rights or the sanctity of life. They are determined to be the last predator standing. And then they too will be snuffed out. Unrestrained hubris always leads to self-immolation.

02 September 2012

It may seem impossible to imagine that a technologically advanced
society could choose, in essence, to destroy itself, but that is what
we are now in the process of doing.”
– Elizabeth Kolbert, Field Notes from a Catastrophe: Man, Nature, and Climate Change (2006)PICKS OF THE WEEK